Fracture Behavior of Cross-Ply Laminates Carbon-Carbon Composites

摘要

Notch sensitivity of a cross-ply laminate Carbon-Carbon composite (C/C) was investigated. Double edge notched (DEN) specimen having various notch root radii was used to examine the notch sensitivity of the C/C. With increasing notch root radius, the fracture behavior of the C/C tended to become notch insensitive. The net fracture stress of the narrower width specimen was larger than that of un-notched specimens. However, the opposite tendency was observed in the wider width specimen, although the fracture stress of the un-notched C/C was independent of the specimen width. The point stress approach was applied to predict the fracture stress of the notched C/C as a first order approximation. The fracture of the C/C was successfully explained by setting the characteristic distance to 0.6 mm to 0.9 mm. The characteristic distance implies the existence of the process zone that makes C/C notch insensitive. The fiber bundle bridging mechanism was considered to explain the test result as the toughening mechanism operating at the damaged area. The calculated result shows the reasonable fit with the experimental results.